准一维链状化合物(MSe4)2I(M=Ta、Nb)高压物性研究

拓扑电子材料由于其特殊的电子能带结构表现出许多奇异的物理现象，如量子反常霍尔效应、拓扑磁电效应等，吸引了人们广泛的研究兴趣。准一维链状化合物(TaSe4)2I是典型的电荷密度波材料。最近的研究发现(TaSe4)2I的高温相为外尔半金属，且随温度降低进入电荷密度波态后表现为轴子绝缘体。这些丰富的物理性质使得(TaSe4)2I成为研究以上多种物态之间相互作用的理想平台。本项目中，基于前期低维和拓扑材料高压调控研究基础，申请人选取(MSe4)2I(M=Ta、Nb)体系为研究对象，利用高压手段调控其晶格和电子态，研究(NbSe4)2I常压下可能的轴子绝缘态以及追踪高压下(MSe4)2I(M=Ta、Nb)电荷密度波和轴子绝缘态的演化规律，构建完整的压力-温度相图，并探索压力下可能诱导的其他新奇量子态。本项目的顺利开展将为进一步理解以上不同物态之间相互作用的内在机制提供重要的实验依据。

Based on its unique electronic band structure, topological electronic material exhibits many novel physical phenomena, such as quantum anomalous Hall effect and topological magnetoelectric effect, has attracted widely research interests. Quasi-one-dimensional chain-like compound (TaSe4)2I is a typical charge density wave material. Recently, based on study on its topological band structure, (TaSe4)2I has been confirmed to be a topological Weyl semimetal in its high temperature phase. When (TaSe4)2I enters into the charge density wave state with decreasing temperatre, it turns into an axion insulator. (TaSe4)2I possesses richness physical properties, thus making it become an ideal platform to study the interaction among these different novel states. Here, based on former research experiences on topological and low-dimensional materials, we choose (MSe4)2I(M=Ta、Nb) as the research subject and utilize external pressure as the tool to tune the lattice and electronic states. We will investigate the potential axion insulating state of (NbSe4)2I, trace the evolution of charge density wave state and axion insulating state of compressed (MSe4)2I(M=Ta、Nb) and explore the potential novel quantum states. It will provide important experimental evidence for further understanding the interaction among these states.